Collapsible container



Jan. 23, 1962 J. E. FELLOWES COLLAPSIBLE CONTAINER 2 Sheets-Sheet 1 Filed Oct. 13, 1958 Jan. 23, 1 J. E. FELLOWES COLLAPSIBLE CONTAINER 2 Sheets-Sheet 2 Filed Oct. 13, 1958 3,013,029 CULLAPSHBLE CQNTAINER John E. Fellowes, Wheaten, ilk, assignor to Bankers Box Company, Franklin Park, Ill., a corporation of Illinois Filed Oct. 13, 1958, Ser. No. 766,865 3 Claims. (Cl. 229-39) This invention relates to a collapsible container and particularly to a collapsible storage box having a novel interlocked bottom construction which is easy to assemble and capable of supporting heavy loads for long periods of time.

Although it is not intended to limit this invention to any specific type of container or material of construction, it is particularly adaptable to storage boxes made of relatively soft fibrous material such as corrugated paper, pressed board or the like, and will be described in relation thereto. The high strength and durability of the construction of this invention especially adapts it for those collapsible corrugated paper containers employed for storing files, for shipping relatively heavy materials and for similar uses.

Collapsible corrugated paper containers are in extremely wide use because they combine easy handling and compact storage with inexpensive and economical construction. Well-known collapsible corrugated paper containers are constructed of a continuous piece consisting of side walls and end walls to which bottom and top flaps are connected. Such containers may be assembled simply by folding down the top and bottom flaps so that they are in approximately abutting relationship with each other, and connecting the flaps to each other with glued paper, tape, staples or other fastening means. For many uses, and particularly for storage boxes, such construction is unsatisfactory since it requires that the equipment and material used for assembling such containers be available at the assembly point. Where containers are used in moderate numbers or at places where such equipment is not conveniently kept, some other form of closure is required. Moreover, sealing with gummed paper or staples limits the strength of the final container to the amount of force required to tear the paper or pull out the staples. This is particularly objectionable with respect to the bottom of such a box, which, if it opens, spills its contents.

It is also known to construct collapsible corrugated paper containers so that the various flaps for the top and bottom closures interconnect in cooperative contact with each other to support the load in the box. For example, many boxes are constructed so that a tongueshaped end on one flap is insertable a sufficient distance into a cooperating slot in another flap so that the stiffness of the corrugated board tends to prevent collapse. Constructions such as this fail if the load in the container is so heavy that the box bottom bows out to the point Where the tongue will come out of the slot or the board buckles to such extent that the stiffness of the board can no longer maintain the tongue in its proper position. Containers of this construction are necessarily limited to those uses where the load Within the container is light.

Other boxes are constructed so that the tabs inserted into slots are held by the friction between the surface of the tab and the surface of the material surrounding it. Boxes with this construction are necessarily limited to loads which do not exceed the frictional force of the construction. For heavy loads, tongues are constructed with snap-out ears which form a positive interlock with the slots into which they are inserted. In order to prevent buckling the ears during assembly and thereby destroying their ability to maintain their proper position, the dimensions of the ears are small and when the bottom of ice the box is bowed due to a load, they are twisted out of their cooperating position with the slot and either slip from the slot or tear.

It is one object of my invention to provide a collapsible corrugated paper or paperboard container with a bottom closure that provides a positive interlock that cannot be broken by buckling or slipping.

It is another object of my invention to provide a container with a bottom closure that restrains the load with high friction which is increased as the load in the box is increased.

It is another object of my invention to provide a closure whose ultimate strength depends on the combination of positive interlocking and high friction restraining means which, when operating in combination, distributes the load-holding strain over the entire bottom of the container.

Other objects and advantages of the container of this invention will be apparent from the description and the accompanying drawings, in which:

FIG. 1 is a plan view of a completely unfolded container embodying the elements of my invention;

FIGS. 2, 3, 4 and 5 illustrate in isometric view various steps in the process of assembling the container of FIG. FIG. 1; and

FIG. 6 is a partially cut-away isometric view of the container of FIG. 1 in assembled condition.

In FIG. 1, the elements 11 and 12 are the side walls of the container while the portions 13 and 14 are the end Walls. The side wall 11 has connected thereto a tongued flap 20 which is provided with a tongue 21 at the extreme end thereof. Tongue 21 contains two laterally disposed, extendable, interlocking extensions 22; which, in this embodiment, are scored at positions 23 to facilitate bending at those points. Extensions 22 preferably do not exceed, in length the width of tongue 21, but should be at least /3 of its width in length so that they may be suitably restrained when extended. Side wall 12 has connected to the bottom thereof a slotted flap 30 which contains an elongated tongue-receiving slot '31, the axis of which is parallel in all positions to the plane of side wall 12. Flap 30 also contains two interlocking extension-receiving slots 32 which are spaced from each end of tongue-receiving slot 31 and positioned to receive interlocking extensions 22 when tongue 21 is inserted in slot 31. Slots 32 lie in the same plane as slot 31, but their longitudinal axes are perpendicular to the longitudinal axis of slot 31.

End Walls 13 and 14 have connected thereto flaps 36 and 35 respectively, each of said flaps having end por tions 33 and 37 respectively. 'Flaps 35 and 36 are cut to completely enclose areas of the bottom of the container not covered by flaps 20 and 3t) and to cover slots 32, but not slot 31.

In assembling the container of this invention, the first step is to connect the edge of end wall 14 to the edge of side wall 11. When such connection is made in the usual way. the bottom of the container is folded as illustrated in FIG. 2. The first step in the assembly of the bottom is to fold slotted flap 3h perpendicular to side wall 12 and toward side Wall 11. The next step in the assembly, as illustrated in FIG. 3, is to fold flaps 35 and 36 towards each other and perpendicular to end walls 13 and 14. As may be seen in FIG. 3, the shape of flaps 35 and 36 is such that, in the folded position, they completely cover interlocking extension-receiving slots 32 but they do not cover tongue-receiving slot 31. End portions 37 and 38 extend beyond slot 31 to minimize the area that must be covered by flap 20.

FIG. 3 further illustrates that the interlocking extensions on tongue 21 may be folded so that the entire width of the tongue and the interlocking extensions will pass through slot 31. In this respect, it may readily be seen that interlocking extensions 22 conveniently do not exceed, in length, the width of tongue 21.

FIG. 4 illustrates that, with interlocking extensions 22 folded and flap 20 slightly bowed, tongue 21 and interlocking extensions 22 are insertable through tonguereceiving slot 31 so that the tongued flap Z overlaps substantial portions of flaps 35 and 36, catches them between flaps 2t! and 3%, completely covers the bottom area of the box and connects directly and positively to flap 30.

FIG. 5 illustrated that, in final assembly, tongue 21 is completely inserted into slot 31 and interlocking extensions 22 are spread to extend in either direction from tongue 21 and to make positive interlocking engagement with the edges of slot 32 to hold tongue 21 in place.

FIG. 6 illustrate the inside of the fioor resulting from the above described assembly. Tongue 21 extends through slot 31 and interlocking extensions 22 are inserted in extension-receiving slots 32. From FIG. 6 it may be seen that interlocking extensions 22 are held by slots 32 so they may not be in any position except flat against the bottom of the container even through the bottom is bowed. This construction prevents their buckling and requires that both extensions be sheared at their junctions with the tongues before the bottom of the container can fail. In addition to the positive interlock, applying force to the bottom of the container causes slotted flap 30 to be depressed against the restraining influence of tongued flap 20 catching flaps 35 and 36 therebetween so that a strong frictional relationship exists to resist forces tending to pull the various fiaps apart. This frictional relationship increases as the load on the bottom of the box increases so that, as the load increases, the proportion of it supported by the positive interlock decreases.

Although the container of this invention is subject to many modifications within its scope, the advantages of the construction are obtained by the cooperative action of a tongue and slot in oppositely disposed flaps, with the tongue having extendable lateral extensions which are restrained in their extended positions. Within the invention, the shapes, sizes and positions of the various elements may be modified to adapt the invention to containers of various sizes and shapes or of different materials of construction. Furthermore, the location or identity of some elements may be modified. For example, the interlocking extensions may be restrained with wire loops rather than slots, or the slots may be located in the end wall flaps rather than as shown. The containers of this invention may also be provided with any suitable top closures as shown in FIGS. 1 and 6, or with cutouts or hardware to facilitate closing the top or handling the loaded container.

From the foregoing, it is evident that the combination of a tongue and slot connection in which the tongue has foldable restrained interlocking lateral extensions provides an extremely strong and durable bottom closure for a collapsible container and represents a substantial improvement over other interlocking closures for such containers. The improvement effected by the container of this invention is obtainable very efficiently and economically since the ability of the closure to restrain heavier loads for longer periods is inherent in its shape rather than in the use of greater amounts of material or stronger materials.

I claim as my invention:

1. A collapsible container which comprises in combination two side walls and two end walls, a tongued flap connecting to the bottom edge of one of said side walls, said fiap terminating in a tongue having two laterally extendable interlocking extensions, each of the latter being in length from about /3 to about 1 times the width of said tongue, a slotted fiap attached to the bottom edge of the other of said side walls, said slotted flap containing a tongue-receiving slot whose axis is parallel to the plane of said side wall and two interlocking extension-receiving slots spaced to either side of the long dimension of said tongue-receiving slot and whose axes run parallel to the plane of said end walls, flaps connected to each of said end walls shaped to extend to points between said interlocking extension-receiving slots and said tongue-receiving slot when all of said flaps are folded perpendicular to said side and end walls and toward the center of said container and a top closure flap connected to one of said side and end walls.

2. A collapsible storage box made of a single sheet of paper board material comprising in combination two side walls and two end walls, one of said side walls being fastened to one of said end walls, flaps extending from the top of a side wall adapted when folded inwardly to provide a top for said storage box, and means to retain said top in closed position, flaps extending from the bottom edge of each wall adapted when interfolded to provide an interlocked bottom for said storage box, the flap connected to the bottom edge of one side wall being provided with a tongue-receiving slot whose axis is parallel to the plane of said side wall and being provided with two extension-receiving slots, one at each side of said tongue-receiving slot and each having an axis disposed angularly relative to the axis of said tonguereceiving slot, flaps connected at the bottom of each end wall which when folded inwardly extend partially over said slotted flap and shaped so as to expose said tonguereceiving slot, and a tongued flap extending from the bottom edge of the other said side wall terminating in a tongue having two laterally extendable tongues at each side thereof folded over said first tongue, said tongue assembly being insertable in the longitudinal slot of said slotted flap having its laterally extendable tongues insertable in each of said extension-receiving slots to form an interlocked bottom for said storage box.

3. A collapsible storage box made of a single sheet of paper board material, said box having integral side and end walls with top flaps and bottom flaps extending therefrom, the bottom flaps comprising an interlocking fold when assembled, said bottom flaps comprising a flap extending from one side wall provided with a longitudinal slot centrally located therein, and having lateral slots spaced from each end thereof, a flap extending from each end wall and overlying a portion of said slotted flap when folded, and a tongued flap extending from the other side wall of said storage box having a tongue provided with lateral extensions, said tongue and its extensions being adapted for insertion into the longitudinal slot of said slotted flap, and said extensions being adapted for insertion in the lateral slots of said slotted flap.

References Cited in the file of this patent UNITED STATES PATENTS 

